The popularity of blow molded handleware has grown in recent years as consumers begin to appreciate the ease of use and the non-breakable characteristics of such containers. Handled containers are especially popular in the larger sizes, i.e. containers having a capacity of one quart or greater. Exemplary of products which are often packaged in handleware are starch, bleach, detergent, milk, distilled water, etc.
In the past a class of blow molding machines known as the "inject, extrude and blow" machines have been adapted to blow mold handled containers of large size. In these machines the neck, or finish, of the container is injection molded in an injection mold superimposed on an annular orifice. After the mold is filled from the orifice, the mold is moved away from the orifice as the tube integral with the material filling the mold is extruded through the orifice. The blow mold is then closed between the tube and the neck mold of the orifice pinching the tube shut near the orifice. Blow air is then injected through the neck mold into the tube, and the tube is simply inflated to the configuration of the blow mold. In early attempts to adopt such injection, extrude and blow machines for the manufacture of handled containers, it was found nearly impossible to extrude a tube having both an integral injection finish and a diameter sufficient to provide material properly located in the parison to be pinched shut by the blow mold to form an integral handle upon blowing. This early attempt at forming handleware resulted in the production of much waste material, i.e. flash, which was principally found on the interior and exterior of the handle. Other problems were also recognized, such as uneven material distribution and pin holes in the handle.
Further refinements were made on the inject, extrude and blow process which were claimed to reduce the amount of flash produced and to also provide a container having uniform material distribution. By reducing the amount of flash which must be trimmed from the container, leaks in the container are said to be avoided. Exemplary of these newer machines is the one disclosed in U.S. Pat. No. 3,944,642.
In the newer version the tubular parison integral with the injection molded finish portion of the container is formed in a conventional manner as set forth in U.S. Pat. No. 3,983,199. The preform is then preblown in an intermediate blow mold which has a similar but smaller shape than the final blow mold. The preblow preform has a portion which is of a configuration such that the preform portion which will form the handle will be encompassed within the handle defining portions of the final blow mold. Once the preblown preform is positioned within the final blow mold the preform is blown to its final shape. Even though this machine and process produces a handled container which is free of external flash, there is still produced flash which is in the interior of the handle, i.e. in the space encompassed between the handle and the container.
Handleware may be produced without concurrent production of flash by the apparatus disclosed in U.S. Pat. No. 3,029,471. This apparatus injection forms the handle followed by formation of an extruded tube which is integral with the handle. The tube is extruded to a sufficient length to fill the axial length of an adjacent split blow mold. The split blow mold is closed to capture that portion of the extruded tube beneath the injection molded handle so that that portion of the tube may be inflated to form the container. Since the apparatus passes the molten thermoplastic material through a single orifice for both the injection and extrusion steps, a highly complex timing and mechanical system must be used. Furthermore, temperature control of the injection finish with respect to the extruded tube will be difficult to handle at best.
Therefore it is an object of this invention to provide a process and apparatus for forming handleware which is free of undesirable flash formation and which is the paragon of simplicity.
It is a further object of this invention to provide an apparatus and process which is capable not only of forming flashless handleware, but which is also capable of forming biaxially oriented handleware.